Omicron Hydrae
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Hydra[1] |
| Right ascension | 11h 40m 12.78970s[2] |
| Declination | −34° 44′ 40.7733″[2] |
| Apparent magnitude (V) | 4.70[3] |
| Characteristics | |
| Spectral type | B9 V[4] |
| U−B color index | −0.20[3] |
| B−V color index | −0.08[3] |
| Astrometry | |
| Radial velocity (Rv) | +5.9[5] km/s |
| Proper motion (μ) | RA: −43.24[2] mas/yr Dec.: −1.61[2] mas/yr |
| Parallax (π) | 7.27±0.16 mas[2] |
| Distance | 449 ± 10 ly (138 ± 3 pc) |
| Absolute magnitude (MV) | −0.99[1] |
| Details | |
| Mass | 3.56±0.04[6] M☉ |
| Radius | 5.5[7] R☉ |
| Luminosity | 309[6] L☉ |
| Surface gravity (log g) | 2.87[8] cgs |
| Temperature | 10,495[6] K |
| Rotation | 27.2 days[8] |
| Rotational velocity (v sin i) | 160[6] km/s |
| Age | 252[9] Myr |
| Other designations | |
| ο Hya, CD−34°7610, FK5 439, HD 101431, HIP 56922, HR 4494, SAO 202695[10] | |
| Database references | |
| SIMBAD | data |
Omicron Hydrae (ο Hya) is the Bayer designation for a solitary[11] star in the equatorial constellation Hydra. At one time it bore the Flamsteed designation 25 Crateris, but this is no longer used by astronomers so as to avoid confusion.[12] With an apparent visual magnitude of 4.70,[3] this star is visible to the naked eye. Based upon an annual parallax shift of 7.27 mas,[2] it is located around 449 light years from the Sun.
This is a B-type main sequence star with a stellar classification of B9 V.[4] It has completed an estimated 98.4%±1.1% of its lifetime on the main sequence. With 3.56[6] times the mass of the Sun, it radiates 309 times the Sun's luminosity from its outer atmosphere at an effective temperature of 10,495 K.[6] The rate of spin is relatively high, with a projected rotational velocity of 160 km/s.[6]
References
[edit]- ^ a b Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. XHIP record for this object at VizieR.
- ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
- ^ a b c d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
- ^ a b Houk, N. (1982), Michigan Catalogue of Two-dimensional Spectral Types for the HD stars, vol. 3, Ann Arbor, MI: Department of Astronomy, University of Michigan, Bibcode:1982mcts.book.....H.
- ^ Wielen, R.; et al. (2000), "Sixth Catalogue of Fundamental Stars (FK6). Part III. Additional fundamental stars with direct solutions", Veröffentlichungen Astronomisches Rechen-Institut Heidelberg, vol. 37, no. 37, Karlsruhe: Verlag G. Braun, pp. 1–308, Bibcode:2000VeARI..37....1W, ISBN 3-7650-0536-3.
- ^ a b c d e f g Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
- ^ Stassun, Keivan G.; et al. (2019), "The Revised TESS Input Catalog and Candidate Target List", The Astronomical Journal, 158 (4): 138, arXiv:1905.10694, Bibcode:2019AJ....158..138S, doi:10.3847/1538-3881/ab3467.
- ^ a b Oelkers, Ryan J.; Rodriguez, Joseph E.; Stassun, Keivan G.; Pepper, Joshua; Somers, Garrett; Kafka, Stella; Stevens, Daniel J.; Beatty, Thomas G.; Siverd, Robert J.; Lund, Michael B.; Kuhn, Rudolf B.; James, David; Gaudi, B. Scott (2018), "Variability Properties of Four Million Sources in the TESS Input Catalog Observed with the Kilodegree Extremely Little Telescope Survey", The Astronomical Journal, 155 (1): 39, arXiv:1711.03608, Bibcode:2018AJ....155...39O, doi:10.3847/1538-3881/aa9bf4.
- ^ Gontcharov, G. A. (2012), "Dependence of kinematics on the age of stars in the solar neighborhood", Astronomy Letters, 38 (12): 771, arXiv:1606.08814, Bibcode:2012AstL...38..771G, doi:10.1134/S1063773712120031.
- ^ "* omi Hya". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-01-06.
- ^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
- ^ Wagman, M. (August 1987), "Flamsteed's Missing Stars", Journal for the History of Astronomy, 18 (3): 216, Bibcode:1987JHA....18..209W, doi:10.1177/002182868701800305, S2CID 118445625.
